Archery bow braided spars

ABSTRACT

An archery bow component includes a preform having a plurality of fiber tows braided to each other. A polymeric material is applied to the preform. The polymeric material coats the plurality of fiber tows during molding of the preform. The dispersal of the polymeric material throughout the preform is effected by the braiding of the plurality of fiber tows to each other.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and the benefit of U.S. provisional patent application serial No. 60/417,315, filed Oct. 9, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to archery bows. More particularly, the invention relates to an archery bow having spars formed from a preform including a plurality of fiber tows braided to each other.

[0004] 2. Description of the Related Art

[0005] An archery bow generally includes spars or limbs extending between a riser and a rotating member, such as a cam or wheel. The spars store energy as the bow is drawn, and then release this energy to an arrow when a string is let go.

[0006] One method for manufacturing bow spars involves molding a resin to a plurality of fibers. This manufacturing method has, however, certain drawbacks. First, since the plurality of fibers are not held into place in any way, the resin has a tendency to wash out the plurality of fibers. As a result, the molded spar includes resin rich areas that are completely devoid of the plurality of fibers. Second, there is the possibility that the resin will only flow to portions of the plurality of fibers, thereby leaving a number of the plurality of fibers completely dry. The presence of either the resin rich areas or the dry fibers results in a spar that is weak and susceptible to cracking upon use of the bow.

[0007] Thus, there is a need for a molded bow spar or limb in which a polymeric material is distributed throughout a preform.

SUMMARY OF THE INVENTION

[0008] According to one aspect of the invention, there is provided an archery bow component including a preform having a plurality of fiber tows braided to each other. A polymeric material is applied to the preform. The polymeric material coats the plurality of fiber tows during molding of the preform. The dispersal of the polymeric material throughout the preform is effected by the braiding of the plurality of fiber tows to each other.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0010]FIG. 1 is a side view of an archery bow;

[0011]FIG. 2 is a perspective view of a preform for forming a spar of the archery bow;

[0012]FIG. 3 is a perspective view of the preform and a scrim cloth;

[0013]FIG. 4 is a fragmentary, perspective view of the preform including a reinforcement strip secured thereto;

[0014]FIG. 5 is a fragmentary, perspective view of the preform including a molding pin; and

[0015]FIG. 6 is a perspective view of a molded spar.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring to FIG. 1, an archery bow, generally shown at 10, includes a handle or riser 12 and a pair of limb pockets 14, 16 coupled to the riser 12. Although a compound bow is shown in FIG. 1, it is contemplated that the following description is equally applicable to other bows including, but not limited to, cross bows and recurve bows. A pair of limbs or spars 20 extends between each of the limb pockets 14, 16 and a rotating member 22. As the bow 10 is drawn, the spars 20 store energy that is eventually released to an arrow (not shown).

[0017] Referring to FIG. 2, a preform, generally indicated at 24, for one of the spars 20 includes a plurality of fiber tows 26 continuously braided to each other. The braided plurality of fiber tows 26 encompasses the braiding and intertwining of one bundle of fibers with one or more other bundles of fibers. The braided and intertwined plurality of fiber tows 26 also encompasses the braiding and intertwining of an individual fiber with one or more individual fibers. It is further contemplated that the preform 24 can be formed by securing two or more of the preforms 24 together as a single preform.

[0018] The fibers selected to form the preform 24 include, but are not limited to, fiberglass, carbon fibers, and various fiber composites. Each of the plurality of fiber tows 26 may be made up of many different fiber materials. In addition, each of the plurality of fiber tows 26 may include fibers of varying diameters.

[0019] The preform 24 is an elongated structure that approximates the configuration of the spar 20. To form the preform 24, the plurality of fiber tows 26 is positioned side-by-side so that the plurality of fiber tows 26 are parallel to one another. The braiding of the plurality of fiber tows 26 produces a stable preform 24 that is resistant to deformation. The fiber content and volume of the preform 24 is precisely controlled by a computer. One example of a computer utilized to form the preform is a computer numerical control (CNC) machine.

[0020] The preform 24 includes a base portion 28 extending between first 30 and second 32 ends. A pocket hole 34 is formed at the first end 30 for receiving one of the limb pockets 14, 16. An axle hole 36 is formed at the second end 32 for receiving an axle 38 (shown in FIG. 1). In a preferred embodiment, at least one of the pocket 34 and axle 36 holes is a counterbore. A spacer or dowel 40 is placed within the holes 34, 36 in order to prevent the plurality of fiber tows 26 from filling the holes 34, 36. The spacer 40 is removed from each hole 34, 36 before molding the preform 24 into the spar 20.

[0021] The plurality of fiber tows 26 is arranged in a predetermined, uniform pattern all along the base portion 28 of the preform 24. As a result, a cross section taken at one part of the base portion 28 will appear the same as a cross section taken at any other part of the base portion 28. The plurality of fiber tows 26 is also arranged in a predetermined pattern at the first 30 and second 32 ends of the preform 24 around the holes 34, 36 thereof. The arrangement of the plurality of fiber tows 26 in these predetermined patterns results in a stable preform structure. In addition, the braiding of the plurality of fiber tows 26 to one another ensures that all of the individual fibers are wet-out during the molding process.

[0022] Referring to FIG. 3, a scrim cloth 42 is wrapped around the preform 24. The scrim cloth 42 covers the entire preform 24 between the first 30 and second 32 ends thereof. An adhesive material may be applied along an inner surface 44 of the scrim cloth 42 in order to secure the scrim cloth 42 to the preform 24. The scrim cloth 42 is a dense fabric material that allows for passage of a molding material therethrough to the underlying preform 24 during the molding process. The scrim cloth 42 acts as a runner for spreading the molding material along the preform 24. In addition, the scrim cloth 42 provides structural support for the preform 24.

[0023] Referring to FIG. 4, a reinforcement strip 46 is applied over the scrim cloth 42 adjacent to at least one of the first 30 and second 32 ends of the preform 24. In a preferred embodiment, the reinforcement strip 46 is a woven fiberglass strip. The reinforcement strip 46 defines an aperture 48 that aligns with one of the holes 34, 36 of the preform 24. The reinforcement strip 46 strengthens the preform 24 at the first 30 and second 32 ends thereof around the respective pocket 34 and axle 36 holes.

[0024] Referring to FIG. 5, a molding pin 50 is inserted into the pocket hole 34 at the first end 30 of the preform 24. Although not shown, the molding pin 50 is also inserted into the axle hole 38. The molding pin 50 maintains the shape of each hole 34, 36 during molding of the preform 24. After the molding process is complete, the molding pin 50 is removed from each hole 34, 36. The molding pin 50 is coated with a releasing agent to effect such removal.

[0025] Referring to FIG. 6, to manufacture the spar 20, the preform 24, along with the scrim cloth 42 and the reinforcement strip 46, is first placed in a mold 52. A polymeric material 54 is injected into the mold 52 through an injection runner 56 at a first end 58. The polymeric material 54 is pulled by a vacuum to a second end 60 of the mold 52. The polymeric material 54 passes through the scrim cloth 42 to contact the plurality of fiber tows 26. The braided plurality of fiber tows 26 distribute the polymeric material 54 throughout the entire preform 24. At the same time, the scrim cloth 42 expands to further distribute the polymeric material 54 throughout the preform 24. As a result, all of the individual fibers are coated with the polymeric material 54. It is also appreciated that the plurality of fiber tows 26 may be pre-soaked with the polymeric material 54 prior to initiation of the molding process to further ensure complete wet-out of the fibers.

[0026] The spar 20 may be molded by resin transfer molding, compression molding, hydroforming, or similar molding processes. The polymeric material used in the molding process may be a thermoplastic polymer, a thermoset polymer, or a like material.

[0027] The preform 24 is molded into the exact shape of the spar 20, as shown in FIG. 7, during the molding process. Alternatively, the preform 24 is molded first and then machined to the exact shape of the spar 20 in a later step. The braiding of the plurality of fiber tows 26 guarantees that the plurality of fiber tows 26 remains in place relative to each other as the polymeric material 54 is introduced thereto. Thus, the fibers are distributed evenly throughout the molded spar 20. The spar 20 is, therefore, devoid of any areas that are rich in polymeric material 54, which can contribute to spar failure. In addition, the braiding of the plurality of fiber tows 26 ensures complete wet-out thereof.

[0028] It is hereby appreciated that although the preform 24 has been described with regard to the manufacture of the spar 20, the preform 24 including the braided plurality of fiber tows 26 may also be utilized in the manufacture of other archery bow components. Further, the plurality of fiber tows 26 may be braided to each other in such a way as to form a preform in various shapes and configurations.

[0029] The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described. 

What is claimed:
 1. An archery bow component comprising: a preform including a plurality of elongated fiber tows braided to each other; and a polymeric material applied to said preform for coating said plurality of fiber tows during molding of said preform wherein dispersal of said polymeric material throughout said preform is effected by the braiding of said plurality of fiber tows to each other.
 2. An archery bow component as set forth in claim 1 including a scrim cloth wrapped around said preform for aiding in dispersal of said polymeric material to all of said plurality of fiber tows.
 3. An archery bow component as set forth in claim 2 including a reinforcement strip disposed along said scrim cloth for strengthening said preform.
 4. An archery bow component as set forth in claim 3 wherein said preform includes at least one hole.
 5. An archery bow component as set forth in claim 4 wherein said reinforcement strip includes an aperture aligned with said at least one hole.
 6. An archery bow component as set forth in claim 5 wherein said preform includes a first preform secured to at least one other preform.
 7. An archery bow component as set forth in claim 5 wherein said polymeric material is a thermoplastic polymer.
 8. An archery bow component as set forth in claim 5 wherein said polymeric material is a thermoset polymer. 